The term colonialism may also be used to refer to a set of beliefs used to legitimize or promote this system. Colonialism was often based on the ethnocentric belief that the morals and values of the colonizer were superior to those of the colonized; some observers link such beliefs to racism and pseudo-scientific theories dating to the 18th and 19th centuries. In the western world, this led to a form of proto-social Darwinism that placed white people at the top of the animal kingdom, "naturally" in charge of dominating non-European indigenous populations.